►Warmmixasphalt (WMA) technology has now been successfully used in Ontario for a few years. This shift in usage relates to extensions in construction…
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▼Warmmixasphalt (WMA) technology has now been successfully used in Ontario for a few years. This shift in usage relates to extensions in construction season, reduced emissions, larger compaction windows, and potential fuel savings. This research between Miller Paving Ltd. and the Centre for Pavement and Transportation Technology attempts to better quantify the difference in hot mixasphalt (HMA) and WMA. The object of this study was three-fold.
The first part of the research was to examine the strength characteristics of HMA and WMA as a function of storage time. The purpose of this evaluation was to quantify indirect tensile strength (ITS) and moisture susceptibility of HMA and WMA over time.
The second objective involved evaluating the performance characteristics of HMA and WMA. Resilient modulus and dynamic modulus testing were completed on plant-produced HMA and WMA material, which was used to determine long-term performance properties of both mixes.
The third and final objective of this study was an economic analysis performed to determine the difference in cost for construction and maintenance for the HMA and WMA pavements. This was completed to determine if the cost of the warmmix technology used in the production of the WMA was offset by fuel savings at the plant.
The findings of the research included:
• HMA and WMA had statistically equivalent air voids over a four-week storage period.
• Dry and wet ITS results for the WMA increased over a four-week storage period while the HMA specimens did not show this same increase.
• WMA material had slightly better workability than the HMA material although the values were statistically equivalent.
• WMA mix had higher resilient modulus values than the HMA mix.
• Dynamic modulus testing showed that at high temperatures, WMA showed to be slightly more susceptible to rutting than the HMA mix, and at lower temperatures, the HMA showed to be slightly more susceptible to fatigue cracking than the WMA mix.
• The MEPDG showed that both the HMA and WMA pavements were deemed to be structurally adequate.
• An economic analysis of the HMA and WMA pavements compared a life cycle cost analysis over a 20-year design life which included all costs associated with construction, maintenance, and rehabilitation of both the HMA and WMA and showed that the HMA was slightly more cost effective than the WMA.
• A field trial was performed by Miller Paving Limited on Highway 62 in Madoc, Ontario showed that the WMA material was more effective at maintaining the temperature of the asphalt mixture during long hauling distances.
• Overall the WMA exhibited the same performance properties as the HMA.

► Economic, environmental and engineering benefits promote the rapid implementation of WMA technologies. However, concerns remain based on changes in the production process that may lead…
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▼ Economic, environmental and engineering benefits promote the rapid implementation of WMA technologies. However, concerns remain based on changes in the production process that may lead to moisture susceptibility in the early life as compared to HMA. To evaluate WMA moisture susceptibility during this critical period, standard laboratory tests were used for three field projects each with an HMA control mixtures and multiple WMA mixtures. Different specimen types were also evaluated to capture differences in mix design, quality control/quality assurance, and field performance.
Specimens were evaluated for moisture susceptibility by Indirect Tensile (IDT) Strength, Resilient Modulus (MR) and Hamburg Wheel-Track Testing (HWTT). Specimens for IDT and MR were tested dry and then tested wet after conditioning as described in AASHTO T283 with one freeze-thaw cycle. HWTT was used to assess both moisture susceptibility and rutting potential under repeated loads in the presence of water at elevated temperatures (i.e., 122?F [50?C]), and the output parameters used for evaluation were the calculated Stripping Inflection Point (SIP) and the rut depth at 5000 load cycles.
Based on the results of the laboratory tests performed on PMFC cores acquired at construction and with time, WMA during its early life exhibited inferior moisture resistance when compared to HMA. However, with time, specifically after one summer, the dry and wet properties of WMA became equivalent to those of HMA. For WMA constructed in the fall, the results from this study suggest that the inclusion of recycled asphalt pavement (RAP) or an anti-stripping agent may alleviate possible moisture susceptibility issues in the early life during wet, winter weather conditions.
While some laboratory test results demonstrated that WMA is more moisture susceptible than HMA, field performance reported to date from the three projects used in this study shows no evidence of moisture damage. Therefore the search for a laboratory test to screen mixtures for moisture susceptibility continues.
An alternative approach, applying Griffith crack growth theory and utilizing IDT, MR and air voids% the adhesive bond energy of asphalt mixtures was calculated for Texas field project. This value holds promise for characterizing performance of asphalt mixtures by considering basic properties and grouping into one representative value.
Advisors/Committee Members: Epps Martin, Amy L (advisor), Epps, Jon A (committee member), Glover, Charles (committee member).

►Warmmixasphalt (WMA) represents a group of technologies that allows production of asphalt mixtures at lower temperatures compared to traditional hot mixasphalt (HMA).…
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▼Warmmixasphalt (WMA) represents a group of technologies that allows production of asphalt mixtures at lower temperatures compared to traditional hot mixasphalt (HMA). This results in less fuel consumption and reduction in CO2 ?and fumes emission. This research was conducted in order to provide North Dakota department of transportation (NDDOT) with a thorough study on state of the practice of WMA in USA and compare WMA performance with HMA. Extensive literature study was conducted, collecting reports and field experiment data from DOTs of states with climate similar to ND. Viewpoints of experts in the field were collected and analyzed using a comprehensive survey. These were added to analysis of collected data on WMA performance. The research results suggest using foaming processes (Double Barrel Green in particular) and chemical additives (Evotherm in particular) at this early stage with guidelines for modifications in WMA specification and testing compared to HMA.
Advisors/Committee Members: Abdelrahman, Magdy (advisor).

►Asphalt pavement is the major pavement type worldwide. Today, over 90% highways are paved with asphalt concrete. Like other pavement types, asphalt pavement suffers from…
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▼Asphalt pavement is the major pavement type worldwide. Today, over 90% highways are paved with asphalt concrete. Like other pavement types, asphalt pavement suffers from certain types of damage, which call for maintenance. Billions of dollars are spent on the maintenance of asphalt pavement each year.
To reduce the maintenance cost, satisfactory pavement design that addresses the mechanical and chemical properties of asphalt pavement, is necessary. In pavement design, two of the factors affecting pavement durability are the absorption of asphalt into porous aggregates and the hardening of asphalt due to oxidation. Asphalt absorption reduces the effective binder content in the pavement. Meanwhile, the oxidative hardening of asphalt will eventually lead to pavement fatigue cracking.
This work focused on the properties of flexible pavement materials, especially asphalt absorption process and oxidation kinetics. The objectives were to evaluate and improve the current method of absorption measurement, and to study the oxidation kinetics of warmmixasphalt (a new pavement technology widely used). To achieve these objectives, studies were designed and conducted.
Asphalt absorption in porous materials was systematically studied. A new method for asphalt absorption measurement, using a density gradient column, was developed to measure asphalt absorption in single aggregate particles at a higher precision level. Experimental results showed that asphalt absorption correlated very well with the void volume in asphalt, regardless of the aggregate type. Moreover, the effect of contact time on asphalt absorption was studied. Finally, the asphalt absorption of warmmix materials from loose mix samples was measured using a density gradient column.
Additionally, the oxidation kinetics of warmmixasphalt was investigated. Oxidation kinetics parameters were estimated and used in a pavement aging simulation. Insignificant differences between the warmmix asphalts and the base binder control were found. These oxidation kinetics results provided a better understanding of the pavement performance of warmmixasphalt.
Advisors/Committee Members: Glover, Charles J (advisor), Lytton, Robert L (committee member), Holste, James C (committee member), Holtzapple, Mark T (committee member).

► Recent improvements in warmmixasphalt technologies have spurred an aggressive adoption of these new practices within the asphalt paving industry. Concerns have arisen among…
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▼ Recent improvements in warmmixasphalt technologies have spurred an aggressive adoption of these new practices within the asphalt paving industry. Concerns have arisen among federal and state agencies about the effects of this line of products on the performance of asphalt pavements. An investigation of the effects of lowering mixing, aging and compactions temperatures while varying the loose mix aging time was performed. Hamburg Wheel Tracking, Flow Number, Dynamic Modulus and Fracture Energy testing were used to evaluate mechanistic properties of the materials.

Clements, T. M. (2011). THE EFFECT OF LOOSE MIX AGING ON THE PERFORMANCE PROPERTIES OF WARM ASPHALTS. (Masters Thesis). University of Kentucky. Retrieved from http://uknowledge.uky.edu/gradschool_theses/120

Clements TM. THE EFFECT OF LOOSE MIX AGING ON THE PERFORMANCE PROPERTIES OF WARM ASPHALTS. [Masters Thesis]. University of Kentucky; 2011. Available from: http://uknowledge.uky.edu/gradschool_theses/120

University of Arkansas

6.
Ryan, John William.
The Characterization of Foamed Asphalt Binders Using a Rotational Viscometer.

► Foamed asphalt is a popular technic of vaporizing water into asphalt binder that falls under the umbrella term of warm-mixasphalt. In order to…
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▼ Foamed asphalt is a popular technic of vaporizing water into asphalt binder that falls under the umbrella term of warm-mixasphalt. In order to understand how to adjust mix designs for the use foamed asphalt, methods must be developed for characterizing different foamed asphalt binders. One way to characterize the asphalt binder is through viscosity testing using a rotational viscometer. The standard method of using a viscometer to measure the viscosity of asphalt binder is insufficient when dealing with foamed asphalts, so a new method has been created along with 4 metrics to analyze the data to characterize foamed asphalt binders.
Advisors/Committee Members: Andrew Braham, Kevin Hall, Micah Hale.

►Warmmixasphalt (WMA) has been on the horizon of new asphalt technologies and now it is at the forefront of many research and field…
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▼Warmmixasphalt (WMA) has been on the horizon of new asphalt technologies and now it is at the forefront of many research and field projects. The process of investigating the implementation of WMA is a task that many state and local agencies are now facing. The typical WMA production temperature ranges from 30 to 100yF lower than typical hot-mixasphalt (HMA). This temperature reduction leads to several benefits for asphalt paving. One of the driving forces of WMA research is the potential for a reduction in energy, fuel consumption and emissions. In accord with emission reduction is the reduced fuel consumption which is an attractive economic benefit. Other benefits include longer haul distances, colder weather paving, reduction of asphalt fumes during paving operations, higher recycled asphalt pavement (RAP) content and a less extreme working environment.
The three main types of WMA are organic wax additives, chemical additives, and plant foaming processes. Presented in this study are performance testing results from field produced WMA (and a control HMA) for each of the three main types of WMA technologies. WMA is showing promising results in laboratory testing throughout the United States and Canada; however, one particular distress that has been documented in laboratory testing is moisture damage. It is hypothesized that the lower aggregate temperatures do not allow for complete drying of the aggregate and can lead to stripping.
There are three main objectives to be addressed though this research. The first is to evaluate field produced WMA mixes with a field produced control HMA mix. The second is to identify potential quality control/quality assurance (QC/QA) concerns and determine if reheating a WMA mixture to prepare a sample will impact the performance testing results. The third objective is to address the WMA moisture susceptibility concerns.
The Iowa Department of Transportation produced four field WMA mixes and four control HMA mixes which were used in this research project. Each mix was produced for a different project at different plant locations. The corresponding control mixes to each WMA mix differed only by the WMA additive. For each project, loose HMA and WMA mix was collected at the time of production and binder from the tank was collected for each mix. Field compacted samples were prepared at the job site and laboratory samples were reheated and compacted at a later date. Indirect tensile strength (ITS) and dynamic modulus samples were procured from each mix produced. Half of the ITS and dynamic modulus samples were moisture conditioned according to AASHTO T283. In total, 284 samples were procured from the field produced mixtures for dynamic modulus, flow number and indirect tensile strength performance testing.
The ITS testing results will include peak loads and tensile strength ratios. Each of these values will be considered when performing the data analysis. The dynamic modulus testing results will help to determine the material stress to strain relationship under continuous sinusoidal…

► This thesis aims to contribute to the growing body of warmmixasphalt (WMA) research by evaluating the differences in behavioral properties of three WMA…
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▼ This thesis aims to contribute to the growing body of warmmixasphalt (WMA) research by evaluating the differences in behavioral properties of three WMA mixtures, representing the three warmmix technology (WMT) categories (foaming, chemical additives, and organic waxes), relative to a control hot mixasphalt (HMA) in a specific set of conditions which is not well documented in literature. These conditions are: plant produced mixtures with all virgin aggregates and binder (i.e. no recycled materials) and no additives other than the warmmix technology. These mixtures were evaluated at low, intermediate, and high testing temperatures before and after a set of conditioning protocols (CPs), which utilized varying levels of isolated and combined oxidative, moisture, and freeze-thaw damage. A key feature of this thesis is that damage induced by these CPs has been benchmarked relative to measured field aging effects through studies which evaluated the three WMA mixtures and one HMA mixture used to obtain the results presented here, along with additional mixtures not considered in this thesis.
Advisors/Committee Members: Dr. Isaac L. Howard (chair), Dr. Ben C. Cox (committee member), Dr. Matthew W. Priddy (committee member).

►WarmMixAsphalt (WMA) is a new technology that was introduced in Europe in 1995. WMA offers several advantages over conventional asphalt concrete mixtures. The…
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▼WarmMixAsphalt (WMA) is a new technology that was
introduced in Europe in 1995. WMA offers several advantages over
conventional asphalt concrete mixtures. The benefits include:
reduced energy consumption, reduced emissions, reduced binder
aging, and extended construction season in temperate climates.
Three WMA techniques, Aspha-min, Sasobit, and Evotherm, were used
to reduce the viscosity of the asphalt binder at certain
temperatures and to dry and fully coat the aggregates at a lower
production temperature than conventional hot mixasphalt. The
reduction in mixing and compaction temperatures of asphalt mixtures
leads to a 30 percent reduction in both fuel energy consumption and
emissions that may cause health problems. This research assessed
the performance of WMA mixes and conventional HMA test sections at
the APLF and on an actual road. The research also evaluated the
engineering properties of WMA mixes and conventional
mixes.
Advisors/Committee Members: Sargand, Shad M. (Advisor).

► Increasing concerns on environment and greenhouse effect, coupled with increased construction prices led to the development of new technologies by the Asphalt industry to produce…
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▼ Increasing concerns on environment and greenhouse effect, coupled with increased construction prices led to the development of new technologies by the Asphalt industry to produce Asphalt Concrete (AC) pavements. Extensive research is being done to evaluate the impact and performance of these new technologies. WarmMixAsphalt (WMA) is one of these technologies that allow mixing, production, placing and compaction of asphalt mixes at significantly lower temperatures as compared to the traditional Hot MixAsphalt (HMA) practice. Lower temperatures result in reduced fuel usage, fume exhausts, greenhouse gas emissions, wear and tear at plants; while enhancing worker health and safety conditions. The performance characteristics of asphalt mixtures containing WMA technologies may be affected and should be quantified. A detailed laboratory study has been conducted to evaluate and quantify the performance of different WMA technologies. Eleven mixes from three overlay field projects across Louisiana were taken into consideration. Evotherm, Rediset, Foaming and Latex were different warmmix technologies used. Each project included a companion HMA mixture section to allow comparison of WMA to conventional HMA. Mechanistic tests were conducted on plant produced–lab compacted (PL) specimens to evaluate Rutting (permanent deformation), Fatigue/Fracture and Low temperature cracking performance of the mixtures at high, intermediate and low temperatures respectively. The testing factorial included Dynamic Modulus, Indirect Tensile Strength (ITS), Flow Number (FN), Loaded Wheel Tester (LWT), Beam Fatigue, Semi-Circular Bend (SCB), Dissipated Creep Strain Energy (DCSE), Thermal Stress Restrained Specimen Test (TSRST) and Modified Lottman Test. A Life Cycle Assessment (LCA) has been performed to evaluate the economic and environmental benefits of WMA. Overall, the WMA mixtures showed similar performance compared to that of control HMA mixtures. Asphalt mixtures with Rediset and Latex showed better performance than conventional mixtures with respect to fatigue and permanent deformation. The use of WMA technologies resulted in lesser aging of the binder. Energy assessment has shown a 12-15 % energy savings. On average, $1.61 of cost savings per ton of produced asphalt was observed along with a considerable reduction in air pollutants without any reduction in the mechanistic performance of these mixtures.

This research reports the study of the production, implementation and performance evaluation of warmasphalt mixtures prepared by adding natural zeolites. It was divided into three stages. The first consisted of performing laboratory tests that get to know some properties and the functioning of warmmixasphalt, determining the projects of mixtures which were used in accelerated tests after analysis of specimens produced by different temperatures of manufacturing and compression. The second step consisted of preparing an asphalt plant for conventional mixtures for the manufacture of mixtures at lower temperatures, in temperature settings, and checking the necessary procedures to tailor a pilot plant to produce warm mixtures according to the temperatures of the project. In the last step, the transport, spreading and compaction of warm mixtures and subsequent performance evaluation of pavements were checked, with the use of linear traffic simulator in three tests conducted on two experimental tracks, located in Testing Pavement Area, on Valley Campus of the Federal University of Rio Grande do Sul.

► The first official state Warm-MixAsphalt (WMA) pavement project in Connecticut was constructed between July 20th and 22nd, 2010 and it involved three experimental…
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▼ The first official state Warm-MixAsphalt (WMA) pavement project in Connecticut was constructed between July 20th and 22nd, 2010 and it involved three experimental sections, i.e. one section with a conventional HMA (control section) and two WMA sections with different technologies, wax and foamed asphalt. All three sections are located on Route 70 in central Connecticut. The materials were collected in loose form and reheated and compacted in laboratory conditions (laboratory fabricated specimens). This paper discusses the effect of mix type on the results from several tests conducted in the laboratory, such as Semi-Circular Bending, Hamburg Wheel Tracking, Indirect Tensile, and Disk Compact Tension. The results from the WMA specimens are also compared against conventional HMA specimens. Finally, the paper presents the performance data from all three test sections after the first winter season and correlates these observations with the laboratory results. It was seen that all sections performed very similarly, however there were subtle differences between the WMA sections that may cause performance differences later in their lives.
Additionally, this study examined the Moisture Induced Stress Test (MiST) as a means of identifying stripping potential in asphalt pavements. Material tested in the MiST included field samples from six Long-Term Pavement Performance (LTPP) test sections as well as field and laboratory compacted WMA from the Rt. 70 test sections. Wearing surface cores from the LTPP test sections were run through the MiST and water samples before and after the test were analyzed using Infrared Spectrometry. The warm-mix specimens were MiST conditioned and compared to the traditional Tensile Strength Ratio as well as the change in bulk specific gravities. The results were mixed results of HMA and WMA specimens. Furthermore, the spectroscopic analysis showed potential differences between the mixes.
Advisors/Committee Members: Michael Accorsi, Nicholas Lownes, Adam M. Zofka.

Bernier, A. K. (2012). Laboratory and Field Evaluation of Two Warm-Mix Additives in Connecticut and Validation of an Alternative Moisture Susceptibility Test. (Masters Thesis). University of Connecticut. Retrieved from https://opencommons.uconn.edu/gs_theses/290

Chicago Manual of Style (16th Edition):

Bernier, Alexander K. “Laboratory and Field Evaluation of Two Warm-Mix Additives in Connecticut and Validation of an Alternative Moisture Susceptibility Test.” 2012. Masters Thesis, University of Connecticut. Accessed January 21, 2019.
https://opencommons.uconn.edu/gs_theses/290.

MLA Handbook (7th Edition):

Bernier, Alexander K. “Laboratory and Field Evaluation of Two Warm-Mix Additives in Connecticut and Validation of an Alternative Moisture Susceptibility Test.” 2012. Web. 21 Jan 2019.

Vancouver:

Bernier AK. Laboratory and Field Evaluation of Two Warm-Mix Additives in Connecticut and Validation of an Alternative Moisture Susceptibility Test. [Internet] [Masters thesis]. University of Connecticut; 2012. [cited 2019 Jan 21].
Available from: https://opencommons.uconn.edu/gs_theses/290.

Council of Science Editors:

Bernier AK. Laboratory and Field Evaluation of Two Warm-Mix Additives in Connecticut and Validation of an Alternative Moisture Susceptibility Test. [Masters Thesis]. University of Connecticut; 2012. Available from: https://opencommons.uconn.edu/gs_theses/290

► The emerging use of warmmixasphalt (WMA) technology has led to economic and environmental benefits for transportation agencies and road users. Among these benefits…
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▼ The emerging use of warmmixasphalt (WMA) technology has led to economic and environmental benefits for transportation agencies and road users. Among these benefits is the reduced mixing and compaction temperatures of WMA. However, decreased temperatures may affect the resulting complex modulus to withstand traffic loads. A performance evaluation of WMA over various ‘curing’ periods would determine the evolution of the complex modulus over time. This allows to identify the optimum time for opening WMA paved surfaces to traffic. The effect of curing time on the short-term performance of the warm stone matrix asphalt (warm-SMA), produced with chemical WMA additives, is investigated. The curing periods include: three, six and 12 hours; one, three and seven days; and three, six and 12 weeks.
The main objective of this study is to experimentally characterize the short-term performance of WMA produced with two types of chemical additives: EvothermTM 3G and Rediset® LQ-1106. The results were analyzed for statistical significance and the effect of warm-SMA on the life cycle cost analysis and life cycle assessment was evaluated. It was determined that the warm-SMA had comparable mechanical properties to the conventional SMA, while providing economic and environmental advantages.
Advisors/Committee Members: Al-Qadi, Imad L. (advisor).

►WarmMixAsphalt (WMA) is a name given to different technologies that have the common purpose of reducing the viscosity of the asphalt binders. This…
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▼WarmMixAsphalt (WMA) is a name given to different
technologies that have the common purpose of reducing the viscosity
of the asphalt binders. This reduction in viscosity offers the
advantage of producing asphalt-aggregate mixtures at lower mixing
and compaction temperatures, and subsequently reducing energy
consumption and pollutant emissions during asphaltmix production
and placement. WMA technologies can be classified into two groups.
The first group reduces the asphalt binders' viscosity through the
addition of organic or chemical additives, while the second group
reduces the viscosity of the asphalt binders through the addition
of water. The latter has received increased attention in Ohio since
it does not require the use of costly additives. In spite of the
above-mentioned advantages for WMA mixtures, many concerns have
been raised regarding the susceptibility of this material to
moisture-induced damage and permanent deformation due to the
reduced temperature level used during WMA production. Therefore,
this study was conducted to develop a laboratory procedure to
produce WMA mixtures prepared using foamed asphalt binders
(WMA-FA), and to evaluate their performance in comparison to
conventional Hot MixAsphalt (HMA). This study involved two types
of aggregates (natural gravel and crushed limestone) and two types
of asphalt binders (PG 64-22 and PG 70-22M). A laboratory scale
asphalt binder foaming device called WLB10, produced by Wirtgen,
Inc., was used to foam the asphalt binders. The aggregate gradation
met the Ohio Department of Transportation (ODOT) Construction and
Materials Specification (CMS) requirements for Item 441 Type 1
Surface Course for Medium Traffic. The resistance of WMA-FA and HMA
mixtures to moisture-induced damage was measured using AASHTO
T-283, and the resistance to permanent deformation was measured
using the Asphalt Pavement Analyzer (APA) and the Simple
Performance Test (SPT). Based on the experimental test results and
the subsequent analyses findings, the following conclusions were
made:- WMA-FA mixtures are more workable and easily compacted than
HMA mixtures even though they are produced at lower mixing and
compaction temperatures. - WMA-FA mixtures are slightly more
susceptible to moisture damage than HMA mixtures. However, the
difference is statistically insignificant. Therefore, if designed
properly, both mixtures are expected to meet ODOT's minimum TSR
requirement for the proposed traffic level.- WMA-FA mixtures,
especially those prepared using gravel aggregates and unmodified
asphalt binders are more prone to rutting than the corresponding
HMA mixtures. Therefore, it is recommended to include the APA test
as part of the WMA mix design procedure to ensure satisfactory
performance for rutting.
Advisors/Committee Members: Abbas, Ala (Advisor).

▼ To evaluate the performance of Warm Mixture Asphalt (WMA) with varying amounts of recycled asphalt pavement (RAP) in comparison with Hot MixAsphalt (HMA), comprehensive laboratory and field evaluations were conducted. Mix designs were performed for both WMA with a LEADCAP additive and HMA with large amounts of fractionated RAP materials. Hamburg Wheel Tracking (HWT) test was performed to evaluate the rutting and moisture susceptibility of both HMA and WMA laboratory mixtures. HMA mixtures with up to 50% RAP materials by binder replacement exhibited a better performance than WMA mixtures. However, when RAP materials were increased to 75% both WMA and HMA mixtures showed a superior performance. When a specially designed LEADCAP additive for a mixture with a high RAP content called "RAPCAP" was used, the performance was significantly improved. The existing Asphalt Bond Strength (ABS) test (AASHTO TP91-11) was modified to better evaluate the adhesion bond between asphalt binder and aggregate surface. Based on the modified ABS test results, it was found that the asphalt binder type significantly influenced the adhesion bond. To evaluate the performance of WMA mixtures in the field, test sections were constructed in Iowa, Minnesota and Ohio. The test sections were successfully constructed with less compaction effort than HMA and met the required field densities per each DOT's specification. All HMA and WMA mixtures collected from the test sections passed the HWT and the modified Lottman tests, which indicates high resistance to rutting and moisture damage. The asphalt binders were then extracted and recovered from the field samples then re-graded following AASHTO M320 and AASHTO MP19-10. The recovered asphalt binder grades were found to be higher than the target grades due to the existence of RAP materials in the mixtures except for asphalt binders extracted from WMA mixtures produced using "RAPCAP" additive.
Advisors/Committee Members: Lee, Hosin (supervisor).

► Existing specifications for asphalt cement employ insufficient aging and conditioning times prior to testing and low strains during the actual test which are insufficient to…
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▼ Existing specifications for asphalt cement employ insufficient aging and conditioning times prior to testing and low strains during the actual test which are insufficient to predict asphalt performance, especially if the materials are modified with additives such as those used for warmmix technology. However, slightly modified protocols, like increasing the conditioning time in the bending beam rheometer (BBR) test and increasing the aging duration in the pressure aging vessel (PAV), predict asphalt performance better than the current Superpave™ specification. These improved protocols are published as new test standards through the collaborative effort between the Ontario Ministry of Transportation and Queen’s University.
In this study, the effects of warmmix and other additives on rheological, aging and failure properties are investigated. The properties are measured by regular tests and by modified protocols. The latter include the extended BBR test (LS-308) and the double-edge-notched tension (DENT) test (LS-299). Changes in ductile strain tolerance within base asphalts due to the various additives as measured with the DENT test were found to be very significant. The DENT results like essential work of fracture, we, plastic work of fracture term, βwp, and critical crack tip opening displacement, CTOD, are usually helped to correlate with the cracking distress survey results of the pavement in service. The addition of amide and polyethylene waxes risks increasing the cracking susceptibility in the pavement. They show a negative effect on strain tolerance in the ductile state, which is likely to show up as premature and/or excessive cracking in service which is similar to their physical hardening behavior from low temperature grading and extended BBR testing.

▼ The goal of this study was to evaluate EvothermTM (a chemical package) and foaming (a water-injection method) warmmixasphalt (WMA) technologies to determine their effectiveness in producing high quality open graded friction course (OGFC) mixes. Specifically, this study focused on the effect of the removal of stabilizing additives (fibers and polymers) on the optimum binder content and performance of WMA OGFC mixtures. By focusing on additive removal, this study attempted to evaluate practical production concerns and the possible benefits of WMA technologies combined with OGFC. The EvothermTM WMA and foaming WMA mixes were compared to traditional HMA OGFC by evaluating four main mix design criteria: draindown, moisture susceptibility, permeability, and abrasion resistance. Overall, 10 different mix designs were tested and evaluated for use in OGFC pavements. Both volumetric and performance properties were analyzed to assess the performance of each mix design. The results suggested that WMA technologies have the ability to enable the removal of fiber from OGFC mix designs without significant draindown and to improve the performance properties of OGFC mix designs. This study suggests that there is a high potential for the use of warmmix technologies in OGFC.
Advisors/Committee Members: Putman, Bradley J, Rangaraju , Prasad R, Klotz , Leidy E.

►WarmMixAsphalt (WMA) was introduced in Europe in 1995. WMA is gaining attention because it offers several advantages over Hot MixAsphalt (HMA).…
(more)

▼WarmMixAsphalt (WMA) was introduced in
Europe in 1995. WMA is gaining attention because it offers several
advantages over Hot MixAsphalt (HMA). The advantages include (1)
reduced energy consumption in the asphalt mixture production
process; (2) reduced emissions, fumes, and undesirable odors; (3)
reduced binder aging;and (4) extended construction season in
temperate climates. Moisture damage can be
defined as the effect of environmental factors such as water,
temperature, and air on the performance of asphalt concrete
pavement. The asphaltmix consists of aggregate (in different
sizes) and asphalt binder being compacted to a specified air void
ratio. Due to traffic load with existence of water, asphalt
concrete mix will start to lose adhesion between aggregate and
binder or lose cohesion within the binder
itself. The main objective of this study is to
assess the performance of WMA and HMA in presence of water by using
nano scale techniques and Surface Free Energy (SFE)concepts, and
then compare the results with asphalt pavement traditional
laboratory tests. In this study, the bitumen’s
main functional groups were determined by using Fourier Transform
Infrared (FTIR) Spectroscopy. The mineral compositions of aggregate
were analyzed by using X-Ray diffraction (XRD) technique. Atomic
Force Microscopy (AFM) was used to measure the surface free energy
of aggregate and asphalt binder. It can also be used to make a high
quality (Three Dimensional) images for smooth and leveled surfaces.
Asphaltmix samples were prepared in the laboratory using Superpave
Gyratory Compactor (SGC) with different thicknesses and diameters.
Half of the asphaltmix samples were conditioned to study the
effect of moisture on the performance of the mix. Air void
structure and aggregate orientation of the asphaltmix were
examined by using X-Ray Computed Tomography (X-Ray CT). X-Ray CT
images were analyzed by using computer software called AVIZO Fire
(version 6.3) to measure the air void ratio, void sizes, and void
distribution. Simple Performance Tester (SPT) was
used to perform dynamic modulus test. The test was performed on
both unconditioned and conditioned samples to compare the results.
MTS machine was used to perform the Indirect Tensile Strength (ITS)
on the unconditioned and conditioned asphaltmix samples. Thermal
cracking temperature for compacted asphalt sample was determined by
using Asphalt Concrete Cracking Device (ACCD). The permanent
deformation (Rutting) of asphalt concrete was determined by using
Asphalt Pavement Analyzer (APA). Based on the traditional
laboratory test results, all mixes are high resistant to moisture
damage with slight differences in the performance of HMA over
WMA. Dynamic modulus test results were used as
inputs to find the relaxation modulus and creep compliance. Two
asphalt mixes from two different plants in the state of Ohio were
evaluated. Based on the traditional laboratory
tests results, the performance of the HMA was higher than the WMA
for each project and this…
Advisors/Committee Members: Sargand, Shad (Advisor).

► A recent joint study by Arizona State University and the Arizona Department of Transportation (ADOT) was conducted to evaluate certain WarmMixAsphalt (WMA) properties…
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▼ A recent joint study by Arizona State University and
the Arizona Department of Transportation (ADOT) was conducted to
evaluate certain WarmMixAsphalt (WMA) properties in the
laboratory. WMA material was taken from an actual ADOT project that
involved two WMA sections. The first section used a foamed-based
WMA admixture, and the second section used a chemical-based WMA
admixture. The rest of the project included control hot mixasphalt
(HMA) mixture. The evaluation included testing of field-core
specimens and laboratory compacted specimens. The laboratory
specimens were compacted at two different temperatures; 270 °F (132
°C) and 310 °F (154 °C). The experimental plan included four
laboratory tests: the dynamic modulus (E*), indirect tensile
strength (IDT), moisture damage evaluation using AASHTO T-283 test,
and the Hamburg Wheel-track Test. The dynamic modulus E* results of
the field cores at 70 °F showed similar E* values for control HMA
and foaming-based WMA mixtures; the E* values of the chemical-based
WMA mixture were relatively higher. IDT test results of the field
cores had comparable finding as the E* results. For the laboratory
compacted specimens, both E* and IDT results indicated that
decreasing the compaction temperatures from 310 °F to 270 °F did
not have any negative effect on the material strength for both WMA
mixtures; while the control HMA strength was affected to some
extent. It was noticed that E* and IDT results of the
chemical-based WMA field cores were high; however, the laboratory
compacted specimens results didn't show the same tendency. The
moisture sensitivity findings from TSR test disagreed with those of
Hamburg test; while TSR results indicated relatively low values of
about 60% for all three mixtures, Hamburg test results were quite
excellent. In general, the results of this study indicated that
both WMA mixes can be best evaluated through field compacted
mixes/cores; the results of the laboratory compacted specimens were
helpful to a certain extent. The dynamic moduli for the field-core
specimens were higher than for those compacted in the laboratory.
The moisture damage findings indicated that more investigations are
needed to evaluate moisture damage susceptibility in
field.

▼ Rheological properties of crumb rubber modified (CRM) binder with wax additive were evaluated at high, intermediate and low temperatures. CRM binders were blended using two wax additives and then artificially short-term and long-term aged using the rolling thin film oven (RTFO) and pressure aging vessel (PAV) procedures. Superpave binder tests were carried out on the binders through the rotational viscometer (RV), the dynamic shear rheometer (DSR), and the bending beam rheometer (BBR). The viscosity properties were evaluated using the RV at two testing temperatures of 135°C and 120°C for three different periods of 30, 120, and 240 minutes. In general, the results of this study concluded that (1) the wax additives in asphalt binder obviously decrease the viscosity; (2) the addition of wax additives is effective to get better the rheological properties of asphalt binder in high-temperature; (3) the rubberized mixes with wax additive are expected to have better haul management; (4) the use of crumb rubber positively influence rutting and cracking properties.
Advisors/Committee Members: Lee, Soon-Jae (advisor), Hu, Jiong (committee member), Song, In-Hyouk (committee member).

► Reclaimed asphalt pavement (RAP) is a valuable resource that can be recycled into new asphalt mixtures. In recent years, the continued rise of raw…
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▼ Reclaimed asphalt pavement (RAP) is a valuable resource that can be recycled
into new asphalt mixtures. In recent years, the continued rise of raw material costs has
generated considerable interest in increasing RAP usage. Warmmixasphalt (WMA) is a
modern development in the asphalt industry that can potentially help increase RAP usage
and achieve adequate mixture performance. The purpose of this dissertation is to: 1)
develop a method to characterize the absorbed, inert and effective bituminous
components in RAP; and 2) evaluate performance of high RAP-WMA mixtures for
various pavement applications including airfield surfaces, highway surfaces and highway
bases.
A unique approach was taken to characterize RAP properties that coupled a
dataset of 568 asphaltmix designs spanning five years of practice and testing 100% RAP
with added virgin binder; 394 compacted specimens and 68 loose specimens were tested.
A method to predict RAP absorbed asphalt was developed and shown to yield more
reasonable results than conventional methods which were shown very likely to give
incorrect absorbed asphalt contents in some conditions. The relative effectiveness of
RAP surface asphalt was evaluated and estimates of inert and effective RAP asphalt were
made for a variety of temperature, compactive effort, and warmmix additive conditions.
Results showed different behaviors between RAP sources and between hot and warmmix
temperatures. These results were also observed in volumetrics of high RAP mixtures.
Performance evaluation was based on testing 75 slab specimens and more than
1100 gyratory specimens. Test data indicated a potential for decreased durability as RAP
content increases; however 25% RAP highway surface mixtures and 50% RAP base
mixtures had similar performance to current practice. Low temperature mixture stiffness
testing and thermal cracking analysis indicated slightly increased stiffness with high RAP
and 25% RAP highway surface mixtures that had comparable performance to current
practice. Dry rut testing indicated high RAP mixtures are rut resistant. Moisture damage
testing of high RAP mixtures indicated passing results in tensile strength ratio testing but
potential for moisture damage in loaded wheel tracking. Overall, 25% RAP highway
surface mixtures are recommended for immediate implementation.
Advisors/Committee Members: Dr. Isaac L. Howard (chair), Dr. E. Ray Brown (committee member), Dr. L. Allen Cooley, Jr. (committee member), Dr. Thomas. D. White (committee member).

Doyle, J. D. (2011). CHARACTERIZATION OF RECLAIMED ASPHALT AND PERFORMANCE BASED EVALUATION OF ITS USE IN RECYCLED MIXTURES. (Doctoral Dissertation). Mississippi State University. Retrieved from http://sun.library.msstate.edu/ETD-db/theses/available/etd-08082011-112124/ ;

Chicago Manual of Style (16th Edition):

Doyle, Jesse David. “CHARACTERIZATION OF RECLAIMED ASPHALT AND PERFORMANCE BASED EVALUATION OF ITS USE IN RECYCLED MIXTURES.” 2011. Doctoral Dissertation, Mississippi State University. Accessed January 21, 2019.
http://sun.library.msstate.edu/ETD-db/theses/available/etd-08082011-112124/ ;.

MLA Handbook (7th Edition):

Doyle, Jesse David. “CHARACTERIZATION OF RECLAIMED ASPHALT AND PERFORMANCE BASED EVALUATION OF ITS USE IN RECYCLED MIXTURES.” 2011. Web. 21 Jan 2019.

Doyle JD. CHARACTERIZATION OF RECLAIMED ASPHALT AND PERFORMANCE BASED EVALUATION OF ITS USE IN RECYCLED MIXTURES. [Doctoral Dissertation]. Mississippi State University; 2011. Available from: http://sun.library.msstate.edu/ETD-db/theses/available/etd-08082011-112124/ ;

►Warmmixasphalt (WMA) is an environmental friendly technology that contributes to the workers safety, reduction of energy consumption and emissions. In this study, the…
(more)

▼Warmmixasphalt (WMA) is an environmental friendly technology that
contributes to the workers safety, reduction of energy consumption and emissions. In this
study, the rheological properties of a PG 64-22 asphalt binder blended with Cecabase RT,
Rediset, Evotherm, and Sasobit WMA additives are investigated as a function of
laboratory aging. Binders modified with WMA additives and the control samples were
both aged in the rolling thin film oven (RTFO) at 143°C and at 163°C, respectively. All
samples were then long-term aged in an environmental chamber kept at 60°C. The longterm
aged samples were collected at different intervals during a six-month period.
Rheological data were collected on each aged sample by performing dynamic shear
rheometer (DSR) frequency sweep from 25 to 0.1 Hz. at three different temperatures, i.e.
45°C, 60°C, and 76°C. Samples were also evaluated with the Bending Beam Rheometer
(BBR) and Fourier-Transform Infrared (FTIR) Spectroscopy. Gauss-Newton method was
vii
used for non-linear parameter estimation for modeling the relationship of complex
modulus (G*) with temperature, frequency, and aging. Regression analysis was also used
for modeling BBR creep stiffness and BBR m-value. Although FTIR results show higher
oxidation levels for control than all WMA samples, DSR and BBR results show that
Sasobit tends to behave closely to control while Cecabase, Evotherm, and Rediset exhibit
lower stiffness than both.
Advisors/Committee Members: Prozzi, Jorge Alberto (advisor), Bhasin, Amit (committee member).

► Transportation services play an important role in the Canadian economy, and social activities as well as Canada's competitiveness in the global economy. As one of…
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▼ Transportation services play an important role in the Canadian economy, and social activities as well as Canada's competitiveness in the global economy. As one of the most valuable systems of transportation in Canada, 90 percent of all goods and services are transported via trucks over an extensive land area characterized by diverse landscapes and harsh environments. These unique characteristics of Canada, coupled with other challenges including an aging road network and highway infrastructure, limited finances, and environmental considerations provide great incentive to decision makers at federal, provincial/territorial, and municipal government levels to consider new and innovative ways to fund road transportation infrastructure. In an effort to evaluate two innovative pavement technologies applicable in both urban and rural areas, this research project is focused on (1) Coloured Hot MixAsphalt (CHMA) and (2) WarmMixAsphalt (WMA).
The intent of the CHMA research study was to characterize the structural, functional, and environmental characteristics of the coloured asphalt design by analyzing laboratory and field performance. This research was focussed on providing innovative and sustainable solutions, which can be effectively used in Canada as means of ensuring durability and high performance throughout the material’s life cycle.
To achieve the research objectives, materials collected during paving operations and materials produced under controlled laboratory conditions were systematically evaluated at CPATT to capture the impact of colouring pigment on the mixture’s strength. Results provided in this thesis suggest that pigmentation can adversely affect the performance and proper steps have to been taken to mitigate such effect: including using softer binder and lower Dust Proportion (DP) in the mixture. The state-of-the-art AASHTOWare Mechanistic-Empirical (M-E) Software was employed to complete the most accurate level of analysis, referred to as “Level 1”. ME analysis outputs were then used to develop prediction models for a design life of 50 years that can be used to establish Life Cycle Cost Analysis (LCCA). Based on LCCA analysis Bus Rapid Transit (BRT) lane structure surfaced with CHMA was found to be significantly more expensive to construct and maintain than a similar structure surfaced with HMA located in York Region. However, this cost difference is expected to decrease in near future as contractors are becoming more familiar with the mixture’s design and production techniques.
This research further evaluated the performance of WMA technology by using different Performance-Graded Asphalt Cement (PGAC) sources modified with three types of WMA additives (Evotherm 3G, Rediset LQ, and SonneWarmix) in combination with two types of aggregate of pink granite and trap rock diabase. Results obtained in this comprehensive research were statistically analyzed to verify the significance of the results. All information collected from a combination of qualitative and quantitative laboratory test methods…

► In recent years, a group of technologies has been introduced in the United States that allows producing asphalt mixtures at temperatures 30 to 100oF lower…
(more)

▼ In recent years, a group of technologies has been
introduced in the United States that allows producing asphalt
mixtures at temperatures 30 to 100oF lower than what is used in
traditional hot mixasphalt (HMA). This group of technologies is
commonly referred to as WarmMixAsphalt (WMA). From among these
technologies, foamed WMA produced by water injection has gained
increased attention from the asphalt paving industry in Ohio since
it does not require the use of costly additives. This study
evaluated the low-temperature performance of foamed WMA and
compared it to traditional HMA. Two asphalt binders (PG 70-22 and
PG 64-28), two aggregate types (limestone and crushed gravel), and
two aggregate gradations (12.5 mm NMAS and 19.0 mm NMAS) were used
in this study. The low-temperature behavior of the asphalt mixtures
was evaluated using the thermal stress restrained specimen test
(TSRST). In addition, the low-temperature properties of the asphalt
binders were measured using the bending beam rheometer (BBR). This
allowed for comparing the fracture temperature obtained from the
TSRST to the low-temperature performance grade obtained using the
BBR test.In general, the foamed WMA mixtures exhibited warmer
fracture temperatures and lower fracture stresses in the TSRST than
the traditional HMA mixtures. This indicates that the HMA mixtures
have better resistance to low-temperature cracking. It was found
that the binder grade had the most significant effect on the
fracture temperature followed by the mix type, while the aggregate
type had the most significant effect on the fracture stress
followed by the binder grade and the mix type. The fracture
temperatures measured in the TSRST were also found to be consistent
with the low-temperature performance grades obtained using the BBR
test.
Advisors/Committee Members: Abbas, Ala (Advisor).

► In this thesis, atomic force microscopy (AFM) was used to investigate moisture damage and the healing characteristics of warmmixasphalt (WMA) and compare it…
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▼ In this thesis, atomic force microscopy (AFM) was used
to investigate moisture damage and the healing characteristics of
warmmixasphalt (WMA) and compare it to those of hot mixasphalt
(HMA) at the nano-scale level. Furthermore, AASHTO T 283 test
method was used to evaluate moisture damage in WMA and HMA mixtures
at the macro-scale level. AFM Force spectroscopy technique was used
to measure the cohesive and adhesive forces in the asphaltmix
using a group of chemically functionalized AFM tips under dry and
wet conditions while tapping mode imaging technique was used to
obtain topographic and phase images for the asphalt binders. Two
types of performance grade binders were evaluated in this study: a
neat asphalt binder PG 64-22 and a polymer modified binder PG
70-22M. Four WMA technologies were investigated: Advera, Sasobit,
Evotherm Advera, and foamed WMA. The results of the AFM imaging
showed “bee- like” structures in most of the tested samples.
Sasobit additive was the only WMA technology that significantly
affected the “bee-like” structures by increasing their lengths and
reducing their widths. In addition, Sasobit resulted in increasing
the relative stiffness of dispersed domains containing the
‘bee-like’ structure in comparison with the flat asphalt matrix for
both types of binders. Based on the force spectroscopy tests the
polymer modified PG 70-22M HMA and WMA samples were found to be
less susceptible to moisture damage compared to the PG 64-22
samples. The inclusion of WMA additives improved the adhesive
forces for both types of binders while its effect on the cohesive
forces was less significant. Sasobit had the least improvement on
the adhesive forces and resulted in reducing the cohesive forces in
both types of binders this could be related to the lower indirect
tensile strength that were obtained for the Sasobit mixtures. The
adhesive forces were reduced after conditioning of the control and
WMA PG 64-22 binders. Sasobit and Advera had the highest reduction
which could be related to the inferior tensile strength ratio
obtained from their mixtures. However, Evotherm and control PG
64-22 adhesive and cohesive forces were not significantly affected
by conditioning. AFM results also showed a good correlation between
the adhesive force results and AASHTO T 283 results. The healing
experiments showed that most WMA processes improved the healing
rate except Sasobit which reduced the crack closure rate. Finally,
this study provides a new approach for evaluating the healing
characteristics of asphalt binder and a better understanding of the
WMA characteristics at a nano-scale level. In addition, it
demonstrated the capability of the AFM to characterize and examine
the nano-structural properties of asphalt paving
materials.
Advisors/Committee Members: Nazzal, Munir (Advisor).

One way to produce WarmMixAsphalt (WMA) consists in adding chemicals to bitumen. Although several! kinds of additives are available on the market the mechanisms of this technology remains still not well understood. This thesis realized within a partnership between TOTAL and the Laboratory of Tribology and Systems Dynamic is focus on three axes to get a better understanding of these mechanisms. One singularity of our approach is due to the fact that experiments were performed at industrial processing temperatures (90°C- 165°C). ln a first lime, a rheological study has shown that bitumen exhibits a Newtonian behaviour at mixing and compacting temperatures. Bitumen viscosity mainly depends on temperature but in not very affected by the chemical additivation. We suggest that the bulk rheology is not adapted to understand the phenomena which are involved and we propose…

► An increase in environmental awareness and energy concerns had recently prompted efforts to make pavement construction cheaper and more environmentally friendly. Warmmixasphalt (WMA)…
(more)

▼ An increase in environmental awareness and energy concerns had recently prompted efforts to make pavement construction cheaper and more environmentally friendly. Warmmixasphalt (WMA) is an asphalt mixture production technology that promises to reduce production costs and greenhouse gas emissions. Foamed asphalt binder is increasingly being used to produce WMA. This dissertation addresses several issues related to the use of foamed asphalt binder for WMA applications. The first objective of the research presented in this dissertation is to develop a method and metrics to precisely quantify the characteristics of asphalt binder foams. Laboratory measurements were obtained using the newly developed method to evaluate the extent and stability of foams produced using different asphalt binders at different water contents and laboratory foaming devices. Results demonstrate that the method developed is promising in terms of its ability to provide a detailed history of the behavior of foamed asphalt binder as the foam collapses. In addition, results indicate that the method is sensitive to distinguish between foaming characteristics of different asphalt binders as well as different water contents and foaming devices. The second objective of this study was to relate intrinsic properties of the asphalt binder to its foaming characteristics. A physical model was developed for expansion of asphalt binder foam based on foam physics and fluid mechanics of micro-droplets. The model relates foamant water and asphalt binder mixing efficiency with the surface tension of the asphalt binder. The model can be used to predict which binder can be effectively foamed and used, and whether any chemical modification to the binder is necessary to achieve the same. Results indicate that only a small percentage of water is effective in foaming the asphalt binder. The last objective of this research was to evaluate the influence of foaming on asphalt binder residues and mixture workability and coatability. The influence of foaming process on the rheological properties of asphalt binder residue was investigated. In addition, the significance of foamed asphalt binder characteristics on mixture workability and coatability was evaluated. Results from this last part of the study can be used to optimize binder foaming such that the resulting mixture is coated and compacted without compromising performance.
Advisors/Committee Members: Bhasin, Amit (advisor), Li, Wei, doctor of mechanical engineering (advisor), Prozzi, Jorge A (committee member), Zhang, Zhanmin (committee member), Juenger, Maria G (committee member).

► In recent years, a new group of technologies has been introduced in the United States that allow producing asphalt mixtures at temperatures 30 to 100oF…
(more)

▼ In recent years, a new group of technologies has been
introduced in the United States that allow producing asphalt
mixtures at temperatures 30 to 100oF lower than what is used in
traditional hot mixasphalt (HMA). These technologies are commonly
referred to as WarmMixAsphalt (WMA). From among these
technologies, foamed WMA produced by water injection has gained
increased attention from the asphalt paving industry in Ohio since
it does not require the use of costly additives. This type of
asphalt mixtures is advertised as an environmentally friendly
alternative to traditional HMA and promoted to have better
workability and compactability. In spite of these advantages,
several concerns have been raised regarding the performance of
foamed WMA because of the reduced production temperature and its
impact on aggregate drying and asphalt binder aging. Main concerns
include increased propensity for moisture-induced damage
(durability) and increased susceptibility to permanent deformation
(rutting). Other concerns include insufficient coating of coarse
aggregates, and applicability of HMA mix design procedures to
foamed WMA mixtures. This dissertation presents the results of a
comprehensive study conducted to evaluate the laboratory
performance of foamed WMA mixtures with regard to permanent
deformation, moisture-induced damage, fatigue cracking, and
low-temperature (thermal) cracking; and compare it to traditional
HMA. In addition, the workability of foamed WMA and HMA mixtures
was evaluated using a new device that was designed and fabricated
at the University of Akron, and the compactability of both mixtures
was examined by analyzing compaction data collected using the
Superpave gyratory compactor. The effect of the temperature
reduction, foaming water content, and aggregate moisture content on
the performance of foamed WMA was also investigated. Furthermore,
the rutting performance of plant-produced foamed WMA and HMA
mixtures was evaluated in the Accelerated Pavement Load Facility
(APLF) at Ohio University, and the long-term performance of
pavement structures constructed using foamed WMA and HMA surface
and intermediate courses was analyzed using the
Mechanistic-Empirical Pavement Design Guide (MEPDG). Based on the
experimental test results and the subsequent analyses findings, the
following are the main conclusions made:- In general, comparable
laboratory test results were obtained for foamed WMA and HMA
mixtures prepared using 30oF (16.7 °C) temperature reduction, 1.8%
foaming water content, and fully dried aggregates. Therefore, the
performance of the resulting foamed WMA is expected to be similar
to that of the HMA.- Surface foamed WMA mixtures had comparable
rutting performance in the APLF to that of the HMA mixtures. This
was also the case for intermediate foamed WMA and HMA mixtures.
These results indicate the field performance of the foamed WMA
mixtures is similar to that of the HMA mixtures.
Advisors/Committee Members: Abbas, Ala (Advisor).